December 11, 2007
10:00 AM (EST)

News Release Number: STScI-2007-44

Hubble Finds that Extrasolar Planet Has a Hazy Sunset

December 11, 2007: A team of astronomers, led by Frederic Pont from the Geneva University
Observatory in Switzerland, has detected for the first time strong evidence of
hazes in the atmosphere of a planet orbiting a distant star. The new Hubble
Space Telescope observations were made as the extrasolar planet, dubbed HD
189733b, passed in front of its parent star in an eclipse. As the light from the star
briefly passes through the exoplanet's atmosphere, the gases in the atmosphere
stamp their unique spectral fingerprints on the starlight. Where the scientists had
expected to see the fingerprints of sodium and potassium, there were none;
implying that high-level hazes (with an altitude of nearly 2,000 miles) are
responsible for blocking the light from these elements.